SWITCH DEVICE

Abstract: The present invention is related to a manually operated switch device for the control of electrical equipment. The electrical elements of the switch are assembled in a housing (28) and the mechanical elements are mounted on a body piece (15) attached to the housing (28). The invention is based on adapting at least one linearly transferrable slide member (14) to the said body piece (15), said slide member having contact or guide surfaces adapted to cooperate with the stationary contacts (26). To the slide member (14) is connected via at least one spring-type element (10) a power-spring-arming plate (11), which is movable parallel with slide member, in such a manner that during the movement of said power-spring-arming plate (11), the slide member (14) is moved correspondingly under the force exerted by power springs (10). By virtue of this arrangement, the switching phase occurs always in a consistent manner irrespective of the speed used for rotating the switch operating lever (1).

Description: Switch device The present invention is related to a manually operated switch device for the control of electrical equipment according to the preamble of claim 1. For switches employed in electrical equipment, the switch position or the switch status must be secured so that an uncontrolled change of the switch status cannot occur. An inadvertent starting of an electrical apparatus occuring due to, e.g., vibration or a strong shock and causing the movement of the switch to a wrong position may launch even the most dangerous hazard situations as a result of unintentional starting of equipment. Inadvertent switching-on of electric power in a circuit may also be hazardous during, e.g., maintenance operations. Corresponding¬ ly, unintentional toggling of a switch to the zero position, that is, switching off the current from an electric circuit may cause machinery damage due to uncontrolled stopping of actuators. Due to such risks, reliable latching of equipment switches in their ON and OFF positions, respectively, must be secured with the help of, e.g., spring-loaded means. Positive latching of a switch position can be implemented by means of, e.g., a cam attached to the switch operating shaft, whereby the cam is followed by a spring-loaded detent lever. The detent lever is provided with a guide slot suited to accommodate a guide pin fixed to the body structure of the switch. The loading spring of the detent lever is adapted about the detent lever and compressed between the guide pin and the meeting point of the detent lever with the cam. When the switch is in its ON position or its OFF position, respectively, the spring latches the switch positively in its set position and prevents uncontrolled rotational movement of the switch operating shaft. As the shaft is rotated, the spring is compressed between the guide pin and the cam tip. After the cam tip is rotated to its top dead center position, the toggling point of the cam/detent system is attained and as the cam is further rotated over its TDC position, the spring pushes the cam and the attached switch operating shaft to its opposite position. However, such a switch construction has some drawbacks. Although the spring can latch the switch positively in a correct position at the ends of the shaft rotational travel, the operation of the switch is rather uncontrolled in the middle of the shaft rotational travel. In the TDC position of the cam/detent mechanism, the spring force is oriented perpendicular to the longitudinal axis of the cam/detent combination, thus being exerted onto the switch operating shaft and not exerting a rotational force on the switch operating shaft and the guide pin. Consequently, this sector of the rotational travel forms an undetermined position of the switch setting, in which the switch may remain after operation by a careless user. The mutual friction between the switch members makes such a position uncontrollable and relatively easily permits the switch to assume this intermediate position. As the intermediate position coincides with the TDC position of the cam/detent mechan¬ ism, the position is quite unstable. Therefore, a switch left in this intermediate position may readily toggle from this intermediate position due to, e.g., a small shock to either limit position. Consequentially, such an uncontrolled change of switch position can cause an inadvertent starting of equipment or switching-on of power in an electric circuit supposed to be at zero voltage. Obviously, a hazardous situation occurs. In addition to that discussed above, a conventional switch has the drawback that the operating speed of the switch is dependent on the operator action. This property degrades the electrical performance specifications of the switch. When the switch is operated using, e.g., too low torque, the switching action does not take place at sufficient speed, whereby an arc will be formed between the contacts that can destroy the switch very quickly as the energy released by the arc obviously has the greater burning effect the longer the arc is maintained. In addition to inadvertent arcing, the switch can be willfully misused by keeping the switch in a position that makes a marginal connection via the burning arc. Obviously, such a misuse destroys the switch extremely rapidly. It is an object of the present invention to achieve a switch construction offering distinct and secure latching in the OFF position and the ON position, respectively, during the operation of the switch. It is a further object of the invention to achieve a switch construction in which the operating member always assumes a position clearly indicating the status of the switch and is capable of actuating the switch contacts at a high speed independent of the manual actuating speed exerted by the operator. The invention is based on providing the switch mechanism with at least one linearly movable slide member with contacts adapted for compatible interaction with the stationary contacts of the switch. To the slide member is connected via at least one spring-type member such as a parallel with the slide member movable power-spring-arming plate which during the moving of said plate causes the slide member to move correspondingly under the force exerted by said springs. More specifically, the switch according to the invention is characterized by what is stated in the characterizing part of claim 1. The invention offers significant benefits. The greatest benefit of the invention is that the switch consistently performs a distinct and unambiguous toggling from one state to another, and the construction of switch device inhibits setting the switch to any intermediate position. The switch is latched in both the ON position and the OFF position both mechanically and via a spring-exerted force to the end of positively securing the switch in the desired position. Furthermore, the switch includes a mechanical force-disconnect means which performs forced disconnection of welded contacts in the case such welding might occur. If the adherence of the welded contacts is so strong as not to permit even a forced disconnection thereof, the switch operating means automati¬ cally returns to the ON position thus removing any ambiguity of the switch state. The power-spring-arming plate controls the connect/disconnect function entirely independently of the operator interaction and consistently at a high speed, because toggling phase is carried out in a controlled fashion actuated by tensioned springs at a constant speed independent of the rotational speed at which the operator rotates the switch operating means. Hence, the switch disclosed herein is inherently immune to any kind of misuse. In the following, the invention will be examined in more detail with reference to the attached drawings, in which: Figure 1 is an exploded view of a switch according to the invention; Figure 2 is a top view of the body piece of the switch illustrated in Fig. 1 ; Figure 3 is the body piece illustrated in Fig. 2 shown in a sectional view along the line A - A; Figures 4 - 6 are detailed view of the different members of the switch; and Figures 7 - 10 are diagrammatic illustrations of the switch mechanism in its different operating positions. The switch according to the invention is assembled into a body piece 15. The space of the body piece 15 at the assembly cavity side houses the members of the operating mechanism, while the other side in the illustrated embodiment houses a contact bridge 16, which communicates via a slanted surface with a lower slide member 14. The contact bridge 16 is movably attached via springs 27 to a housing 28. The moving contacts of the switch are situated on the contact bridge 16, while the opposite contacts are stationary mounted relative to the body piece 15. Switching is performed by moving the lower slide member 14, which then moves via the slanted surface 24 the moving contacts 25 of the contact bridge 16 relative to the stationary contacts 26. Alternatively, the moving contacts may be directly mounted on the lower slide member and the stationary contacts directly in the body piece 15, respectively. As the structure of contacts is irrelevant to the function of the invention, their detailed description is omitted herefrom. In assembly of the elements into the assembly cavity, the lower slide member 14 is inserted first, said member having a hole in its center and accommodations 21 for springs to both sides of the hole. Power springs 10 are adapted into these accommodations 10 and the springs are mounted between retaining pegs 12 situated at both edges of the power-spring-arming plate 11 which is placed over the lower slide member 14. Over the power-spring-arming plate 11 is placed an upper slide member 8, which is connected to the lower slide member 14 by means of two tabs 20, of which one is located in the lower slide member 14 and the other in the upper slide member 8. The switch operating shaft 4 passes through holes provided in the lower slide member 14, the power-spring-arming plate 11 and the upper slide member 8. To both sides of the switch operating shaft 4 are adapted detent leaf springs 3 which rest against detent teeth made on the operating shaft 4. The end of the switch operating shaft 4 has cams 6, and transfer teeth 7, 23 are provided on the shaft perimeter remaining between the cams 6 and the detent teeth 5. The assembly cavity of the body piece 15 is sealed by a cover 2, and the operating lever 1 of the switch shaft is attached to that end of the switch operating shaft 4 passing through the cover 2. The bottom of the assembly cavity of the body piece 15 is provided with locking slots 17 incorporating locking teeth 18 at that side of slots which are closer to body piece center axis. The locking tooth 18 is a projection having a straight side oriented to the center of the body piece and projecting orthogonally from the sur¬ face of the locking slot 17, while the other side of the projection is slanted relative to the straight side and oriented in the opposite direction. Said slanted side separ¬ ates from the end of the locking slot 17 a locking space 19. The lower slide member 14 is provided with resilient fingers 22 which become inserted in the locking slots 17 when the lower slide member 14 is inserted into the body piece 15. The cams 6 of the switch operating shaft 4 are designed to cooperate with said fingers 22. The side of the hole at the center of the power-spring-arming plate 11 is provided with teeth 13 suited to cooperate with the transfer teeth 7 of the switch operating shaft 4. The side of the hole in the upper slide member 8 is provided with a force- exerting surface 9, which cooperates with the endmost tooth 23 of the transfer teeth 7 at the side of the switch operating shaft 4 when the shaft is inserted in the hole. The function of a switch assembled in the above-described manner from its elements is discussed in the following. The discussion assumes the switch to be initially in a position in which the operating lever 1 of a switch in the OFF position points to the right, and correspondingly, the operating lever 1 points downward when the switch is in the ON position. With reference to Fig. 7, the switch is shown in the OFF position, that is, the load current is switched off. The transfer teeth 7 of the switch operating shaft 4 have driven the power-spring-arming plate 11 to the right side of the assembly cavity and the power springs 10 push the lower and upper slide members 8, 14 to the same side. The first locking finger 22 of the lower slide member 14 is in this position of the switch pushed against the straight side of the locking tooth 18 of the locking slot 17 and this locks in place the lower slide member 14 as well as the upper slide member 8 connected thereto by means of the tab 20. When the switch operating shaft 4 is rotated clockwise, its transfer teeth 7 move the power- spring-arming plate 11 to the left, whereby the power springs 10 are compressed, because the locking finger 22 retains the slide members 8, 14 locked in place against the locking tooth 18 of the locking slot 17. After the switch operating lever 1 is rotated to point approximately downward, that is, to the ON position of the switch, the cam of the switch operating shaft 4 meets the locking finger 22 and lifts it off from the notch of the locking tooth 18 (Fig. 8). The slide members 8, 14 can now move to the left, and are in fact pushed to the left side of the assembly cavity under the pushing force exerted by the power springs 10. With the movement of the lower slide member 14, the electric connection is established at the toggling of the switch to its ON position. During the movement of the lower slide member 14 to the left side of the cavity, the locking finger opposite to the first locking finger drops into the notch of the locking tooth 18 of the locking slot 17, thus locking the lower and upper slide members 14, 8 in place. The final position of the switch is as shown in Fig. 9. Toggling the switch from the ON position to the OFF position occurs in a normal situation in a corresponding manner to that described above for toggling to the ON position. The only difference herein is that the power-spring-arming plate 11 and the slide members 8, 14 now move to the right. However, sometimes the contact surfaces of the switch may become welded together due to, e.g., poor contact. Then, the force exerted by the power springs 10 is not sufficient for separating the contacts, whereby the slide members 8, 14 remain to the left side of the cavity, and the switch cannot open. For such a case, the upper slide member 8 is provided with a force-exerting surface 9, which cooperates with the endmost tooth 23 on the switch operating shaft 4. Said endmost transfer tooth 23 extends slightly higher in the longitudinal axis direction of the switch operating shaft 4 than the rest of the transfer teeth 7, whereby the endmost tooth extends into the hole of the upper slide member 8. In a welding situation of the contacts, the switch is opened in the following manner. After the switch operating lever 1 has been rotated counterclockwise and the cam 6 of the switch operating shaft has released the locking finger 22, the lower slide member 14 and the upper slide member 8 connected to the lower slide member still remain to the left due to contact welding. As the switch operating lever 1 is rotated further, the endmost transfer tooth 23 on the switch operating shaft 4 meets the force-exerting surface 9 of the upper slide member 8, thereby pushing both slide members 8, 14 to the right, whereby the weld between the contacts is generally detached. After the weld detachment, the power springs 10 push the slide members 8, 14 in a normal manner to the right thus setting the switch to the OFF position. If the weld between the contacts is so strong as to persistently resist such a forced separation attempt, the power springs 10 push the power-spring-arming plate 11 and the switch operating lever 1 back to the ON position as soon as the operator releases his grip from the lever, whereby no ambiguity can remain of the actual state of the switch. The switch operating shaft 4 further has a square section comprising a four-lobed 5 divided at equal angles. The detent leaf springs 3 are placed to the side of the switch operating shaft 4 at said cams 5 so close that the cams 5 rest against the leaf springs 3 when the shaft is rotated. Thus, said leaf springs 3 act as a detent for the rotational movement of the switch operating shaft 4 so that the switch operating shaft 4 is clearly positioned at 90° increments. The force exerted by these detent leaf springs 3 must be dimensioned so that the power springs 10 can return the switch operating lever 1 and shaft 4 back to the OFF position in persisting cases of switch contact welding. In addition to the preferred embodiment of the invention described above, the present invention can be implemented in a plurality of alternative manners. For instance, the switch springs can be any desired type of spring elements or similar resilient energy-storing elements. The locking of the slide members can be simply realized using other types of locking means different from the locking fingers described above. A plurality of such locking finger/backing surface combinations are known in the art. Further, the upper slide member can be omitted from the construction and its functions combined with those of the lower slide member. Correspondingly, the mutual placement of the slide members and power-spring- arming plate can be interchanged and the electrical contacts can be adapted to the sides of the switch housing, as well as below it. The contact bridge may be a separate element, or alternatively, the moving contacts can be incorporated in the lower slide member.

Claims: Claims: 1. A switch device for the control of electrical equipment, said device comprising - a housing (28) with stationary contacts (26) adapted thereto to the end of forming an electric contact, - a body piece (15) attached to said housing (28), - a switch operating shaft (4) adapted to said body piece (15) so as to be rotatable about its longitudinal axis, and - moving contacts (25) suited for making a physical contact with the stationary contacts (26) to the end of forming an electric contact, c h a r a c t e r i z e d by - at least one slide member (14) adapted to the said body piece (15), said slide member being linearly movable relative to said body piece (15) so that the moving contacts (25) make an electric contact with the stationary contacts by virtue of the movement of said slide member (14), - at least one power-spring-armirig plate (11) adapted to said body piece (15), said plate being transferrable by the rotation of the switch operating shaft in a parallel direction with said slide member (14), and - at least one spring-type member (10) suited for connecting the power- spring-arming plate (11) to said slide member (14) to the end of transmitting the movement of said power-spring-arming plate (11) to said slide member (14). 2. A switch as defined in claim 1, characterized by - at least one first locking member (22) which is suited for locking said slide member (14) to a first position relative to the body piece (15) and is releasable from its locked position by the rotation of the switch operating shaft (4), and - at least one second locking member (22) suited for locking said slide member (14) to a second position relative to the body piece (15) and is releasable from its locked position by the rotation of the switch operating shaft (4). 3. A switch as defined in claim 2, characterized by - a first slide member (14) which is adapted to one side of said power- spring- arming plate (11) and comprises locking members (22), and - a second slide member (8) which is adapted to the other side of said power-spring-arming plate (11) and is permanently connected to said first slide member (14). 4. A switch as defined in claim 3, characterized in that a hole is provided in the center of said first slide member (14), said second slide member (8) and said power-spring-arming plate (11) so as to permit the insertion of the switch operating shaft (4) through said holes. 5. A switch as defined in claim 4, characterized by a projection adapted on the switch operating shaft (4) and by a force-exerting surface (9) at the side of the hole in the second slide member (8), both details adapted to cooperate so that the second slide member (8) is force-controlled movable by the rotation of the switch operating shaft (4), whereby a projection (23) of the shaft (4) meets said force-exerting surface (9).

Inventors: MATTLAR HARRI, PUSSINEN MATTI, MATTLAR, HARRI, PUSSINEN, MATTI
Applicants: ABB STROEMBERG KOJEET OY, MATTLAR HARRI, PUSSINEN MATTI, MATTLAR, HARRI, PUSSINEN, MATTI
Application year: 1994
Main classification: H01H9
IPC codes: H01H19